1. Field of the Invention
The present invention relates to a medical image management apparatus, a medical image management method and a recording medium stored therein a program for managing images that have been captured by a medical image imaging apparatus, which images a subject.
2. Description of the Related Art
In recent years, a medical image storage communication system (PACS: Picture Archiving and Communication System) has been used. In the PACS, image data generated by a medical image imaging apparatus, such as a CT apparatus, an MRI apparatus, and an echography apparatus (ultrasonography apparatus), is stored in a management server so that image data corresponding to a distribution request input from a client terminal, such as a medical image display apparatus, can be transferred.
In the medical image imaging apparatus, such as the CT apparatus, a multiplicity of slice images are generated by using a helical scan method that can continuously capture slice images of a subject by imaging. The slice planes of the multiplicity of slice images are perpendicular to the body axis (the slice planes are axial planes), and the generated slice images are sent to a management server. An operator who performs image diagnosis or the like at a client terminal sequentially obtains the multiplicity of slice images generated by the medical image imaging apparatus from the management server. Further, the operator reconstructs, from a three-dimensional image composed of the multiplicity of slice images, slice images of slice planes in a direction corresponding to the region of the subject represented in the three-dimensional image, and displays the reconstructed slice images. Further, the operator performs projection processing on the three-dimensional, image to generate a pseudo three-dimensional image, and displays the pseudo three-dimensional image.
Recently, as a medical image imaging apparatus that can acquire high-density slice image data at high speed has become widely used, precise projection data about the subject can be collected. However, the amount of generated image data has increased, and the time period necessary for transfer and reconstruction has become long. Therefore, there is a problem that a response to an image request by the operator is delayed.
Ordinarily, a management server stores a plurality of slice images (axial images) generated by a medical image imaging apparatus. The plurality of slice images are generated by imaging the subject with respect to axial planes of the subject. The management server sequentially distributes the stored axial images in response to a distribution request input from a client terminal. Accordingly, when axial images are displayed as initial images at the client terminal, it is possible to sequentially display each of the axial images in the order of receipt thereof without waiting until transfer of all of the axial images is completed. Therefore, a time lag between the time of sending a request for a desired image to the management server and the time of displaying the image on the display screen is relatively small.
Meanwhile, for example, in diagnosis of a chest image, coronal images are often used, because the slice direction of the coronal images is similar to the direction of an image obtained by general X-ray radiography. When a coronal image, instead of the axial image, is displayed as an initial image, it is possible to improve the efficiency of diagnosis. However, when a slice image of a slice plane (for example, a coronal plane and a sagittal plane) other than the axial plane is displayed as an initial image at the client terminal, at least a part of data representing each of all the axial images is used to generate the slice image. Therefore, it is impossible to display a desirable slice image until transfer of all of the axial images is completed. Hence, the time lag is large.
Meanwhile, U.S. Patent Application Publication No. 20060267976 (Patent Document 1) proposes a method for reducing the delay of display. In the method, image data is stored in a management server as compressed image data. Further, when a client terminal requests voxel data that is necessary to generate a desirable image, compressed image data for restoring the requested voxel data is provided. The client terminal decompresses the provided compressed image data, and generates and displays a desirable image.
However, in the method disclosed in Patent Document 1, a user needs to perform a complex operation for specifying how the image should be displayed. Further, the compressed data that has been sequentially transferred in response to the specification operation by the user needs to be decompressed, and an image is generated from the decompressed voxel data. Therefore, a time lag is generated between the request for the image and the display of the image.